1. Field of the Technology
The present invention relates to communication technology, particularly to a communications network system for implementing mixed services and the method thereof.
2. Background of the Invention
Flexible number plan is typically used for a unified management of subscriber numbers within a local communications network. With the flexible number plan, each subscriber will actually have two numbers, one is a logical number published to the public, and the other is a physical number deciding the home network of the subscriber. With such a number issuing solution, the physical number of a subscriber may be changed when the subscriber is transferring among the switching offices, while the logical number thereof remains unchanged. In this way, the subscriber will be of mobility. Apart from among fixed subscribers, the flexible number plan can be implemented among both fixed and mobile subscribers, achieving a function of comprehensive number issuing.
At present, the number used by a subscriber of a Public Switched Telephone Network (PSTN) is tied up with the actual port, device, and network the subscriber actually uses. The location and terminal office to which a subscriber belongs determines the number used by the subscriber, which means that a PSTN subscriber number is of no mobility.
A solution of number portability (NP) has been proposed to solve the problem of moving the number of a PSTN subscriber. NP is typically realized with an intelligent network and a subscriber in the NP solution has two numbers as well, the logical number in public use and the physical number defining the home office. The NP solution with an intelligent network includes primarily the NP process for the calling that converts the physical number of the calling to the logical number thereof for use in displaying the calling number and charging correctly and the NP process for the called that converts the called logical number a subscriber has dialed to the called physical number for use in addressing the called subscriber.
Though the mobility of a number can be realized through the NP solution with an intelligent network, the following problems still exist:                1. As there are various types of switching equipment in the switching offices of a network and some types are unable to insert access codes automatically in accordance with user subscription information, it is difficult to implement the triggering of the above-mentioned service in the entire network, setting limits to the wide application of NP service.        2. Since the NP service requires accessing the call to an intelligent network and converting the number before continuing with the subsequent process, a great number of detour routes are created.        3. An NP service is only a simple process for number conversion while an intelligent network is designed to deal with complicated services. Implementation of an NP service with an intelligent network will occupy a great deal of resources of the intelligent network. As a result, there will be a major impact on the capacity of an intelligent network when an NP service is provided for a large number of subscribers.        